Mixing scheme and process for the preparation of a refinish coating composition

Abstract

The present invention refers to a mixing scheme containing a plurality of pigmented base paint compositions having defined colors and optionally one or more non-pigmented base paint compositions comprising at least one rheology controlled base paint composition containing at least one pigment selected from the group consisting of inorganic pigments, di-keto-pyrrolo-pyrrole type pigments, organic liquid crystal type pigments and carbon black and having the following rheology profile (1) an initial viscosity V 1 at 20° C. of 65 Pa s or greater when measured at a shear rate of 10 −3 s −1 , (2) a viscosity V 2 at 20° C. when measured at a shear rate of 10 −3 s −1 immediately after subjecting to a shear rate of at least 15 s −1 whereby the viscosity V 2 is 700 Pa s or less and is less than or equal to 70% of V 1 ; (3) 24 hours after subjected by shaking to a shear rate of at least 15s −1 a viscosity V 3 at 20° C. of at least 140% of V 2 and be at least 55 Pa s, to a process of preparing a refinish coating composition using the mixing scheme of the present invention, to a refinish coating compositions obtainable therefrom, to a process of coating a substrate using the refinish coating composition and to a coated substrate obtainable therefrom.

1. A mixing scheme comprising:
 a plurality of pigmented base paint compositions having defined colors and comprising at least one rheology controlled base paint composition comprising at least one pigment selected from the group consisting of inorganic pigments, di-keto-pyrrolo-pyrrole pigments, organic liquid crystal pigments and carbon black, wherein the at least one rheology controlled base paint composition comprises a thixotropic agent present and in an amount to provide a rheology profile comprising:
 (1) an initial viscosity V 1  at 20° C. of 65 Pa s or greater when measured at a shear rate of 10 −3  s −1 , 
 (2) a viscosity V 2  of 700 Pa s or less and less than or equal to 70% of V 1  at 20° C. when measured at a shear rate of 10 −3  s −1  immediately after subjecting to a shear rate of at least 15 s −1 ; and 
 (3) a viscosity V 3  of at least 140% of V 2  and at least 55 Pa s within 24 hours at rest after being subjected to a shear rate of at least 15 s −1 , 
 wherein the resulting base paint compositions are resistant to settlement as a result of this rheology profile. 
 
 
     
     
       2. The mixing scheme of  claim 1 , wherein the initial viscosity V 1  at 20° when measured at a shear rate of 10 −3  s 1  is above 80 Pa s. 
     
     
       3. The mixing scheme of  claim 1 , wherein the viscosity V 2  is 700 Pa s or less at 20° C. when measured at a shear rate of 10 −3  s −1 . 
     
     
       4. The mixing scheme of  claim 1 , wherein the viscosity V 3  is at least 140% of V 2  within 12 hours after being subjected to shear and is 80 Pa s or greater. 
     
     
       5. The mixing scheme of  claim 1 , wherein the at least one pigment is selected from:
 (1) pigments which are classed as Pigment White in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (2) pigments which are classed as Pigment Black in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (3) pigments which are classed as Pigment Metal in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (4) thin platelets, made of natural mica or synthetically produced substrates, of low refractive index which are coated with thin layers of titanium oxide and/or other metal oxides with high refractive index; 
 (5) iron oxide type pigments which are classed as Pigment Red in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (6) iron oxide type pigments which are classed as Pigment Yellow in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (7) lead chromate type pigments which are classed as Pigment Red in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (8) lead chromate type pigments which are classed as Pigment Yellow in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (9) bismuth vanadate pigments which are classed as Pigment Yellow in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (10) di-keto-pyrrolo-pyrrole pigments which are classed as Pigment Red in the Colour Index classification published by the Society of Dyers and Colourists, American Association of Textile Chemists and Colourists; 
 (11) special effect pigments selected from organic liquid crystals, pigmented coated silica particles, pigmented coated aluminum oxide flakes, vacuum metallized flake, polyester holographic metallized flakes and metallized glass flakes. 
 
     
     
       6. The mixing scheme of  claim 5 , comprising 2, 3, 4, 5, 6, 7 or more rheology controlled base paint compositions. 
     
     
       7. The mixing scheme of  claim 1 , wherein the thixotropic agent is selected from hydrogenated castor oils, pyrogenic silica, and polyureas. 
     
     
       8. The mixing scheme of  claim 7 , wherein the thixotropic agent is a polyurea that is selected from the reaction product of a polyisocyanate, a primary or secondary monoamine and optionally a primary and/or secondary diamine and the reaction product of a primary and/or secondary diamine, a monoisocyanate and optionally a polyisocyanate. 
     
     
       9. The mixing scheme of  claim 1 , wherein the pigmented base composition comprises, in addition to color providing pigments, pigments designed to give visual effects selected from metallic effects and pearlescent effects. 
     
     
       10. The mixing scheme of  claim 1 , wherein the pigmented and the non-pigmented base compositions comprise different or identical binders selected from acrylic resins, polyester resins, polyurethane resins, epoxy resins, polyether resins and alkyd resins, optionally a crosslinker and one or more solvents. 
     
     
       11. A process for preparing a refinish automotive coating composition comprising:
 (a) selecting a predetermined number of pigmented base paint compositions in predetermined amounts, whereby at least one of the pigmented base paint composition is a rheology controlled base paint composition as defined in any of the preceding claims and optionally a predetermined number of non-pigmented base paint compositions from the mixing scheme according to any of the preceding claims so that the refinish coating composition matches a predetermined color after mixing; and (b) mixing the selected base paint compositions. 
 
     
     
       12. A refinish automotive coating composition obtained by the process of  claim 11 . 
     
     
       13. A process for coating a substrate comprising applying the refinish coating composition of  claim 12  onto a substrate and allowing or causing the coating to dry or cure. 
     
     
       14. The process of  claim 13  wherein the substrate is a motor vehicle or a part thereof. 
     
     
       15. A coated substrate obtained by the process of  claim 13 . 
     
     
       16. The mixing scheme of  claim 1 , further comprising (B) one or more non-pigmented base paint compositions.